#!/usr/bin/python3
"""
Host service for Linux Unified Key Setup (LUKS, format 2) devices.

This will open a LUKS container, given the path of the parent
device and the corresponding passphrase.

NB: This will use the custom osbuild udev rule inhibitor mechanism
to suppress certain udev rules. See `osbuil.util.udev.UdevInhibitor`
for details.

Host commands used: `cryptsetup`, `dmsetup`
"""

import argparse
import contextlib
import os
import stat
import subprocess
import sys
import uuid

from typing import Dict, Optional

from osbuild import devices
from osbuild.util.udev import UdevInhibitor


SCHEMA = """
"additionalProperties": false,
"required": ["passphrase"],
"properties": {
  "passphrase": {
    "description": "Passphrase to use",
    "default": "",
    "type": "string"
  }
}

"""


class CryptDeviceService(devices.DeviceService):

    def __init__(self, args: argparse.Namespace):
        super().__init__(args)
        self.devname: Optional[str] = None
        self.lock = None
        self.check = False

    def dminfo(self, name=None):
        """Return the major, minor and open count for the device"""
        res = subprocess.run(["dmsetup", "info", "-c",
                              "-o", "major,minor,open",
                              "--noheadings",
                              "--separator", ":",
                              name or self.devname],
                             check=False,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.STDOUT,
                             encoding="UTF-8")

        if res.returncode != 0:
            data = res.stdout.strip()
            msg = f"Failed to find the device node: {data}"
            raise RuntimeError(msg)

        data = res.stdout.strip()
        data = list(map(int, data.split(":")))
        assert len(data) == 3
        major, minor, count = data[0], data[1], data[2]
        return major, minor, count

    def open_count(self, name=None):
        count = 0
        with contextlib.suppress(RuntimeError):
            _, _, count = self.dminfo(name)
        return count

    def open(self, devpath: str, parent: str, tree: str, options: Dict):
        passphrase = options.get("passphrase", "")

        parent_dev = os.path.join("/dev", parent)

        # Generate a random name for it, since this is a temporary name
        # that is not store in the device at all
        devname = "osbuild-luks-" + str(uuid.uuid4())
        self.devname = devname

        # This employs the custom osbuild udev rule inhibitor mechanism
        self.lock = UdevInhibitor.for_dm_name(devname)

        # Make sure the logical volume is activated
        res = subprocess.run(["cryptsetup", "-q", "open", parent_dev, devname],
                             check=False,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.STDOUT,
                             input=passphrase,
                             encoding="UTF-8")

        if res.returncode != 0:
            data = res.stdout.strip()
            msg = f"Failed to open crypt device: {data}"
            raise RuntimeError(msg)

        print(f"opened as {devname}")

        # Now that device is successfully opened, we check on close
        self.check = True

        # Now that the crypt device is open, find its major/minor numbers
        major, minor, _ = self.dminfo()

        subpath = os.path.join("mapper", devname)
        fullpath = os.path.join(devpath, subpath)
        os.makedirs(os.path.join(devpath, "mapper"), exist_ok=True)
        os.mknod(fullpath, 0o666 | stat.S_IFBLK, os.makedev(major, minor))

        data = {
            "path": subpath,
            "name": devname,
            "node": {
                "major": major,
                "minor": minor
            }
        }
        return data

    def close(self):
        if not self.devname:
            return

        _, _, opencount = self.dminfo()
        print(f"closing (opencount: {opencount})")

        self.lock.release()
        self.lock = None

        name = self.devname
        self.devname = None

        # finally close the device
        res = subprocess.run(["cryptsetup", "-q", "close", name],
                             check=self.check,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.STDOUT,
                             encoding="UTF-8")


def main():
    service = CryptDeviceService.from_args(sys.argv[1:])
    service.main()


if __name__ == '__main__':
    r = main()
    sys.exit(r)